While speaking at a rally at an Omaha high school on Monday, Clinton told supporters one way she plans to do this is by making sure the U.S. has an electrical grid able to distribute energy from renewable sources. The former secretary of state cited Iowa’s use of wind energy as a successful example.

One of Iowa's U.S. Senators says he's surprised at how far the state's wind energy production has come. Iowa continues to lead the nation in wind energy, and Republican Sen. Chuck Grassley was among its early backers. This week the US Department of Energy reported Iowa generates more than 30 percent of its power from wind, the highest percentage in the country. Grassley says back in 1992 when he pushed for tax incentives for wind energy, he didn't expect it would get this big.

Earlier this week, a new report by the US Department of Energy showed that costs continue to decline while turbine technology becomes more efficient. All of this, along with the Obama administration's Clean Power Plan, means wind energy is having a moment.

At the same time utility companies erect modern wind turbines across the Iowa countryside, old fashioned windmills are rusting away on abandoned farmsteads. But there's one man who is out to preserve the crumpled icons, one windmill at a time. Meet the Windmill Wizard.